His coworkers gave him the nickname of "Fantasy Guy" due to his love of the fantasy genre and because he dresses as a Game Master from the MMORPGWorld of Warcraft.

He previously went out on a date with Robin, where it was revealed that he "gets up early to trade on the European Stock Exchange".

Marshall also tried to go by the nickname of "Fantasy Guy" when he created and ran his office's fantasy baseball league. However, Barney told him that they already have a "Fantasy Guy", and so would instead have to be "Sports Guy".